﻿<p><em>IfcShapeAspect</em> allows for grouping of shape representation items
that represent aspects (or components) of the shape of a product. Thereby shape
representations of components of the product shape represent a distinctive part
to a product that can be explicitly addressed.</p>
<p>The <em>IfcShapeAspect</em>'s may have distinct material information or
other distict characteristics that differs from other parts of the product
shape representation.</p>
<blockquote class="note">NOTE&nbsp; The <em>IfcShapeAspect</em> together with
the <em>IfcMaterialConstituent</em> can be used to associate distict material
information to parts of the product shape representation.</blockquote>
<p>Figure 2 indicates the association of material characteristics to shape
aspects.</p>
<table>
<tr>
<td><img src="../../../figures/ifcshapeaspect_fig1.png" alt="shape"></td>
</tr>
<tr>
<td>
<p class="figure">Figure 2 &mdash; shape aspects for associating material</p>
</td>
</tr>
</table>
<blockquote class="extDef">NOTE&nbsp; Definition from ISO 10303-41:<br>
A shape aspect is an identifiable element of the shape of an
object.</blockquote>
<blockquote class="note">NOTE&nbsp; Entity adapted from
<strong>shape_aspect</strong> defined in ISO 10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2.0</blockquote>
<blockquote class="change-ifc2x4">IFC4 CHANGE&nbsp; Attribute
<em>PartOfProductDefinitionShape</em> declared OPTIONAL and extended to type
<em>IfcProductRepresentationSelect</em> with upward compatibility for file
based exchange.</blockquote>
<p class="spec-head">Informal Propositions:</p>
<ol>
<li>If <em>ShapeRepresentations</em> points to shape representations that are
part of an <em>IfcProductDefinitionShape</em>,
<em>PartOfProductDefinitionShape</em> must refer to this instance of
<em>IfcProductDefinitionShape</em>.</li>
<li>If <em>ShapeRepresentations</em> points to shape representations that are
part of an <em>IfcRepresentationMap</em>, <em>PartOfProductDefinitionShape</em>
must refer to this instance of <em>IfcRepresentationMap</em>.</li>
</ol>